Elements, Compunds + Mixtures

Question 1

Define an atom and element, giving examples. (4)

Answer 1

Atoms are the building blocks of everything. (1) Hydrogen Atom (1)

An element is a substance that is made up of only one kind of atom. (1) Hydrogen (1)

Question 2

Structure of an atom and a brief description of the sub
atomic particles; protons, neutrons, and electrons. (5)

Answer 2

Atoms are made up of three smaller particles called protons + (1), electrons -(1) and neutrons o (1).
(+, - and o: represent charge)

The protons and neutrons are contained in the nucleus, the tiny centre of an atom, (1) with smaller electrons orbiting outside the nucleus (1).

Question 3

Recognise the most common elements from the periodic
table and their symbols. (6)

Answer 3

Hydrogen (1) H (1)
Helium (1) He (1)
Iron (1) Fe (1)
…

Question 4

Define a mixture and give examples. (4)

Answer 4

A mixture is formed when two or more elements or compounds are present without being chemically bonded together. (1)

Peas + Sweetcorn (1)
Mixture of Sweets (1)
Mixure of Coins (1)

Question 5

Distinguish between a solute, solvent and solution. (3)

Answer 5

A solution is made when a substance dissolves into a liquid. (1) The liquid is called the solvent. (1) The substance that has been dissolved is called the solute. (1)

Question 6

Describe how to separate mixtures using filtration. Be able to fully label a diagram of filtration. (2)

Answer 6

Filtration is a method for separating an insoluble solid from a liquid. When a mixture of sand and water is filtered:

1. The sand stays behind in the filter paper (it becomes the residue)
2. The water passes through the filter paper (it becomes the filtrate)

Question 7

Describe how to separate mixtures using evaporation. Be able to fully label a diagram of evaporation. (2)

Answer 7

Evaporation is used to separate a soluble solid (i.e. a solid that dissolves) from a liquid.

Question 8

Describe how to separate mixtures using simple distillation. Be able to fully label a diagram of distillation. (2)

Answer 8

Simple distillation is a method for separating the solvent from a solution. (2)

Question 9

Describe how to separate mixtures using fractional distillation. Be able to fully label a diagram of fractional distillation. (2)

Answer 9

Fractional distillation is a method for separating a liquid from a mixture of two or more liquids.

Question 10

Describe how to separate mixtures using chromatography. Be able to fully label a diagram of chromatogrophy. (2)

Answer 10

Paper chromatography is a method for separating dissolved substances from one another.

Question 11

Define a compound and give examples of common
compounds.

Answer 11

A compound is a pure substance that is made from more than one element. In a compound, elements are chemically bonded together, which makes it very difficult to separate them. (1)
Water - H2O (1)
Carbon Dioxide - CO2 (1)
Sodium Chloride - NaCl (1)

Question 12

Does a chemical reaction must occur for a compound to occur? (1)

Answer 12

Yes. (1)

Question 13

Define a chemical change and give examples of chemical
changes. (3)

Answer 13

A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed. (1)

Wood Burning. (1)
…

Question 14

List some ways you can observe a chemical reaction has
taken place. (3)

Answer 14

Bubbles – Many chemical reactions you see in the science lab make a chemical which is a gas, so you see bubbles. (1)

A colour change – If the new chemicals are a different colour from the original chemicals, there will be a colour change. (1)

A large energy change – Many chemical reactions give off lots of energy, like burning, and a few absorb energy, so they feel cold. (1)

Question 15

How to write a word equation and what a reactant and a
product are. (4)

Answer 15

A word equation represents a chemical reaction using the names of the substances involved. Word equations do not show any chemical symbols or formulae. (1) The reactants are on the left of the chemical equation, and the products on the right. (1)

In a chemical reaction, reactants are the substances that react together, and products are the substances formed. (1)

Question 16

How to name compounds, ‘ide’ and ‘ate’ and the
exceptions of diatomic elements such as chlorine. (9)

Answer 16

When 2 elements mix their name ends with -ide.

Iron + Oxygen → Iron Oxide (1)

When 3+ elements mix and one is Oxygen, their name ends with - ate.

Copper + Sulphur + Oxygen→ Copper Sulphate. (1)

Diatomic elements are not compunds! They are elements that are rarely found separate in nature. They are:

Hydrogen, Nitrogen, Flourine, Oxygen, Chlorine, Iodine, and Bromine. (7)